Large integrated circuits (IC) are constructed from known cells that are connected together within the IC and custom structures that are defined in terms of artwork on various layers in the IC. In addition, the IC design can be divided into a plurality of different chips that are connected together using wire bonds or the like. Any given device within the IC can be viewed as having a set of artwork that defines structures, typically polygons, on the various layers of the IC or the individual chips. In general, a device also has electrical properties that are important in simulating the IC to determine if the final IC will work as intended. Known devices such as transistors are typically provided by the fabrication facility in a form that automatically generates the artwork for those device in the layout file that represents the IC. The known cells and remaining artwork for an IC are typically collected into a computer aided design file (CAD) which forms the input to various analysis tools that check the design to be sure that the design is consistent with the particular fabrication facility. These tools also check the design against the schematic of the circuit being implemented and generate other information on the layout of the device.
A typical large scale IC can have millions of devices. Correlating a device from the schematic with the corresponding artwork in a complex IC is a challenging task. Current tools do not provide a database that provides an easily accessible listing for each device in the IC that allows a designer to find a specific device and the artwork associated with that device.
In addition, the manner in which existing design and layout tools define devices is time consuming and error prone. A device is defined in a rule set in terms of the artwork associated with the device. If a device is a “compound device” that is constructed from a number of more elementary devices, the compound device must be specified as if the elementary devices do not exist. That is, the designer must specify the artwork for each of the elementary devices within the device definition of the compound device. In addition to increasing the complexity of device definition, this type of “flat” device definition obscures the true nature of the compound device.
In addition to the devices that are intentionally within the IC, there are “devices” that arise from the interactions of various structures in the ICs. For example, two conductors that are close to one another in one area of the IC may form a “device” that is a coupler between the two conductors. Finding such devices in an IC presents significant challenges using existing design tools.